Computer Geeks! What OS for my Server System?

I am getting an older server system for use as a slave for Cubase with Vienna Ensemble Pro. I will have to purchase a root drive and install an operating system.

I want a Windows OS that is light weight, and able to be accessed via Remote Desktop. I was looking at Windows Server 2016… until I saw the costs. And those cheapo ones on ebay I can’t trust as far as I can through a neutron star.

In short, I want a functioning Windows OS for the least expense.

Thoughts?
Thanks.

Windows 10 Pro is your only other option then.